Differential Stimulation of NAD Kinase and Binding of Peptide Substrates by Wild-Type and Mutant Plant Calmodulin Isoforms

Liao, Birong; Gawienowski, Margaret; Zielinski, Raymond E.

doi:10.1006/abbi.1996.0092

Cited by 55 publications

(41 citation statements)

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“…A diversity of Ca 21 sensors, including Ca 21 -dependent protein kinases and calcineurin-like proteins, likely endow plants with a highly specific and complex Ca 21 signaling network (Luan et al, 2002). Consistent with earlier reports (Lee et al, 1995(Lee et al, , 1997Liao et al, 1996), we observed a differential response of native NADK activity to a variety of CaM-related proteins, including seven that had not previously been cloned or studied. Interestingly, CML10, which is about 64% identical to the conserved CaM but possesses a unique 42-residue Figure 6.…”

Section: Discussionsupporting

confidence: 91%

“…Previous reports have shown that both C-terminal and N-terminal regions of CaM are important in achieving full activation of plant NADK (Liao et al, 1996;Lee et al, 1997), and, thus, it is perhaps surprising that we observed full activation of Arabidopsis NADK by CML10. Although the function of the C-terminal extension in CML10 is unknown, our results suggest that this extension acts independently of the hydrophobic regions important in the activation of NADK (Liao et al, 1996). By contrast, the more divergent CaM-related proteins we examined were only able to weakly activate native NADK above background levels.…”

Section: Discussionmentioning

confidence: 51%

“…Effect of Various CaM-Related Proteins on Native NADK Activity Previous studies on pea (Pisum sativum) NADK have demonstrated a differential response of the enzyme to various CMLs unique to plants (Lee et al, 1995(Lee et al, , 1997Liao et al, 1996). We examined the responsiveness of Arabidopsis native NADK to seven novel Arabidopsis CML recombinant proteins and a previously described protein, CML10 (originally termed CaBP-22; Ling and Zielinski, 1993).…”

Section: Characterization Of Recombinant and Native Nadk Activity Andmentioning

confidence: 99%

“…Moreover, plants possess not only the evolutionarily conserved form of CaM but also an extended family of CaM-like proteins (CMLs) not present in other organisms (McCormack and Braam, 2003). Physiological roles for many of these putative Ca 21 sensors remain to be established, but several show differential regulation of plant NADK (Liao et al, 1996;Lee et al, 1997). Furthermore, the potent Ca 21 mobilizing agents, cADP-Rib and nicotinic acid adenine dinucleotide (NAADP) are derived from NAD and NADP, respectively, and play important roles in intracellular Ca 21 signaling in both plants (Navazio et al, 2000) and animals (Patel et al, 2001).…”

mentioning

confidence: 99%

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Cloning and Characterization of Two NAD Kinases from Arabidopsis. Identification of a Calmodulin Binding Isoform

et al. 2004

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NAD kinase (NADK; ATP:NAD 2#-phosphotransferase, EC 2.7.1.23), an enzyme found in both prokaryotes and eukaryotes, generates the important pyridine nucleotide NADP from substrates ATP and NAD. The role of NADKs in plants is poorly understood, and cDNAs encoding plant NADKs have not previously been described to our knowledge. We have cloned two cDNAs from Arabidopsis predicted to encode NADK isoforms, designated NADK1 and NADK2, respectively. Expressed as recombinant proteins in bacteria, both NADK1 and NADK2 were catalytically active, thereby confirming their identity as NADKs. Transcripts for both isoforms were detected in all tissues examined and throughout development. Although the predicted catalytic regions for NADK1 and NADK2 show sequence similarity to NADKs from other organisms, NADK2 possesses a large N-terminal extension that appears to be unique to plants. Using recombinant glutathione-S-transferase fusion proteins and calmodulin (CaM)-affinity chromatography, we delineated a Ca 21 -dependent CaM-binding domain to a 45-residue region within the N-terminal extension of NADK2. Although recombinant NADK2 was not responsive to CaM in vitro, immunoblot analysis suggests that native NADK2 is a CaM-binding protein. In Arabidopsis crude extracts, CaMdependent NADK activity was much greater than CaM-independent activity throughout development, particularly in young seedlings. A native CaM-dependent NADK was partially purified from Arabidopsis seedlings (K m NAD 5 0.20 mM, K m Mg 21 2ATP 5 0.17 mM). The enzyme was fully activated by conserved CaM (S 0.5 5 2.2 nM) in the presence of calcium but displayed differential responsiveness to eight CaM-like Arabidopsis proteins. Possible roles for NADKs in plants are discussed in light of our observations.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 51%

Section: Characterization Of Recombinant and Native Nadk Activity Andmentioning

confidence: 99%

mentioning

confidence: 99%

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Cloning and Characterization of Two NAD Kinases from Arabidopsis. Identification of a Calmodulin Binding Isoform

et al. 2004

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“…Interestingly, their CaM domains are 100% identical to AtCaM-2, which does not contain a CTE. Although no studies have been conducted yet on AtCaM-5, it has been shown that AtCaM-2 has a higher ability to activate NAD kinase than AtCaM-4 or AtCaM-6 (28).…”

Section: Oscam61 Is One Of Five Calmodulins Known To Be Present Inmentioning

confidence: 99%